1999 suburban 5.7 vortec

[94 saturn sl1 2000 saturn sc2]

Greetings all,


Well i just purchased a 1999 Suburban K1500 with the 5.7 vortec engine. 146,000 miles no body rust.. After about 500 miles of driving I have noticed especially when the engine is not up to operating temprature there is a noticable lag in throttle response. the engine idles at about 550 to 600 rpm when fully warmed. It seems a bit rough at idle to me but soess not stall . Tune up time or simply a TPS replacement ? I put 20 ounces if Marvel Mystery oil in the tank this morning before filling it thinking possibly some deposits on injectors ect... Techron will go in next.. any thoughts appreciated.

 

[tomcat27]

clean the throttle body where the throttle plate is. If you are carefull, you can also remove the IAC motor and clean the pintle. check all vacuum lines.

 

[c502cid]

Originally Posted By: tomcat27
clean the throttle body where the throttle plate is. If you are carefull, you can also remove the IAC motor and clean the pintle. check all vacuum lines.


+1 to the throttle plate

 

[The_Jeff]

Yeah the idle thing sounds like a vacuum leak.

 

[Smoky14]

I'd run a compression check,some of these puppies had soft cams and the lobes would start to go flat at 125K or so miles.

 

[94 saturn sl1 2000 saturn sc2]

Originally Posted By: Smoky14
I'd run a compression check,some of these puppies had soft cams and the lobes would start to go flat at 125K or so miles.


god lets hope not.. lol Im guessing it is definetly a fuel issue.. dirty ect, This thing sat for a period of time.. could be a vacuum leak.. will have it examined within the next week. MPG has been 15.1 and 14.9 respectively. No oil consumption . In 800 miles the oil still looks clean and is on the full mark. im hoping the engine is solid as I plan to build the interior and add some goodies outside. thanks much for your ideas .

 

[stevejones]

Fuel pump and/or SCPI unit; but start with a tune-up and check fuel pressure. Wait until you get the harsh 1-2 shifts from the PWM solenoid leaking...

 

[artificialist]

Those things were notorious for bad intake manifold gaskets, spray carb cleaner all around the intake manifold and listen for changes in RPM.

Also, I am surprised that an engine with factory roller cams has problems with flattening lobes.